US Secretary of State Mike Pompeo called Saudi Crown Prince Mohammed bin Salman to discuss regional challenges including the tension in the Gulf, Yemen and Iran's role. State Department Spokeswoman Morgan Ortagus said Mr Pompeo "thanked the Crown Prince for Saudi Arabia’s support and engagement across many regional challenges" during their call on Wednesday. Maritime security and US attempts to build a coalition of 60 plus countries to secure freedom of navigation in Strait of Hormuz were also discussed. Ms Ortagus also said that the top US diplomat and the crown prince "discussed other bilateral and regional developments, including countering the Iranian regime's destabilising activities." So far, only the United Kingdom has publicly announced its intent to join the US-led effort, also known as Sentinel Programme. Tension between Washington and Tehran has soared since US President Donald Trump pulled the United States out of a nuclear deal with Iran last year and imposed punishing sanctions. Twelve months on from the US withdrawal, Iran responded by suspending some of its commitments under the nuclear deal. Iran meanwhile shot down an American drone in June, with Trump saying he called off retaliatory air strikes at the last minute, and the United States says it has since downed one and possibly two of Tehran's unmanned aircraft, which the Islamic republic has denied. On Yemen, Mr Pompeo and the Crown Prince "reaffirmed their strong support for UN Special Envoy Martin Griffiths’ efforts to advance the political process," the statement read. Following the UAE announcement of redeployment in Yemen, the US and Mr Griffiths have been attempting to break the stalemate and make movement on the political solution. "The Secretary and the Crown Prince also discussed other bilateral and regional developments, including countering the Iranian regime’s destabilizing activity and human rights," the statement read.